I downloaded the demo for this game to "try before you buy", Loved it, game ran without a hitch, completed the demo and thought I should buy the game,Purchased a used copy off Amazon for £15, and loaded it up, First problem came when there was no install code anywhere on the box or in/on the manual,after checking the variuose websites and other links,we eventualy got an entry code, Then after this you need to register your copy of the game before it will let you play,( says you don't need to register to activate and no personal information will be collected, yet I was unable to activate without first registering)
Eventualy we got the game up and running, but the game crashed on several occasions with a blue screen Page_fault_irq_not_equal or something like that, So I done a memory check, Came back to a memory fault so I removed 1 gig(2X512MB) and the game was started up, however on startup it we could not run and a message on the screen says this game has been loaded into to many different machines and will need to be re-activated.
This is DRM at it's worst.

True about "used" gaming programs.. or any others. Once registered with that unique COA string, it is not acceptable for any other install.. unless the registration process for the previous use has been deleted.
There is a big market for "used" game programming.. but if it entails registration of the product for use again, there may be a large can of "dead fish" found.
Perhaps there should be added an "unregister product" process? But how many users would adhere to that process before passing on unwanted software?

Karl, the problem is not that it is a used copy of the game, the game will only run if the disc is in the drive.
The problem is that after re-registering and then getting the activation code the whole thing has to be gone through once again because I reduced the amount of installed memory, As I said DRM in a bad light.

I have several games that require the install CD in order to play.. even though I have duly registered the game, and done the updates that should allow playing without the install CD present.
For piracy protection, the developers have some specific files that do not get copied to the hdd. The installed program would create a reference link to ensure that the OEM disk was present.
Having reduced system memory shouldn't cause problems with programming.. unless the memory quotient is below a desired level.
The only alternate route to not needing to provide the OEM disk would be having a multi-disk reader connected via a LAN or dedicated link.

See if there are any recent patches or updates that may allow playing without the presence of the install disk. There should be some "read me" files associated with those patches, that indicate their intent.
If you had been able to start the game without the install disk after registering and updating, and now it reverts to need of the install disk, then the programming file regarding that update may have been corrupted. It happened to two of my games.. I just accept the inconvenience.

i've found nothing wrong with the game running...nor have any of my friends with it. i bought it for 25$ brand-new from best buy last week...saved over 50%.

one of my friends had a copy which said his activation code was already in-use by a different user, and would not let him play. he promptly returned the game to best buy for a replacement which worked without a reinstallation perfectly.

The game ran fine on my rig, went 17 hours without a hitch, Now I'm without my main rig until the wife finishes the game I don't have anything bad to say about the game just the tight restrictions caused by the DRM, If you have something that is incompatable with the game you can't swap out any components to check without the game locking you out.